The phase of light propagating through a waveguide is sensitive to changes in the refractive index of the waveguide. Additives to the interior or surface which modify the molecular structure of the waveguide affect light propagation. Thus waveguide devices such as interferometers can be made into sensors which directly convert these changes into optical signals. Further modifications which engineer specific functions - such as molecular recognition or catalytic elements - have the potential to allow detection of specific analytes. The physical and chemical flexibility of modern polymeric materials make them strongly advantageous over other materials for this type of application. Hence, we propose to construct a novel class of waveguide sensors using a variant of a recently developed polyamide polymer, uniquely engineered to allow modification by recognition elements after device fabrication. The proposed recognition element-analyte tests represent a range of analytes (inorganic and organic, polar and apolar, low and high M.W.), chosen to sample the broad array of possible conditions required of a new type of sensor, and to touch on areas of commercial analytical interest (e.g., selective detection of metal ions, and drug and metabolite enantiomers, etc.). The simplicity of the modification strategies allows sampling of this array of conditions to proceed in parallel. In this way, we hope to ensure development of one or more prototypes, each capable of a specific analytic task, as proof of the principle of waveguide sensing, and as a point of entry into the development efforts of Phase II. PROPOSED COMMERCIAL APPLICATION Diagnostics is a rapidly growing field with medical, agricultural, environmental and industrial markets; there, robust, low-cost, target- specific sensors play critical roles. In medicine, devices of the sort we propose could ultimately be tailored to monitor for levels of substances in situ (e.g., sensing specific toxins, metabolites, etc.). In manufacturing or environmental contexts, such devices would be suitable for effluent monitoring, in the detection of either inorganics or organics.